Zhao Lianhai, father of a child sickened by the milk, has rallied other families through a website he created. He said the parents were called or visited by local officials wanting the families to back out of the lawsuits and accept a government-sanctioned compensation plan giving 2,000 yuan (S$449) to most victims.

At least one family has done so, Mr Zhao said.

Phones at the Zhoukou city health bureau rang unanswered on Tuesday.

The alleged intimidation tactic comes after the executive vice-president of the country's highest court, Shen Deyong, said earlier this month that families who rejected the government's compensation plan were welcome to file lawsuits against the dairies.

More than 600 families have demanded higher compensation than the government plan offers - one-time payouts using money from dairies named in the scandal.

Families that take the money can't sue for more unless they can prove they were forced to agree to the compensation plan, lawyers have said.

It was not clear why local officials would try to stop families from suing the dairies after Mr Shen said China's courts were prepared to accept the cases.

But his announcement came shortly before the start of the country's annual legislative session, a politically sensitive period when authorities routinely clamp down on protests, petitioners and other signs of social unrest.

Infant formula contaminated with the industrial chemical melamine was blamed for killing at least six babies and sickening nearly 300,000 in the scandal that began in September.

Unscrupulous middlemen are accused of adding melamine, which is high in nitrogen, to watered-down milk to fool quality tests for protein content. Melamine can cause kidney stones and kidney failure. -- AP